archive-tar.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include <time.h>
   5 #include "cache.h"
   6 #include "commit.h"
   7 #include "strbuf.h"
   8 #include "tar.h"
   9 #include "builtin.h"
  10 #include "archive.h"
  11
  12 #define RECORDSIZE      (512)
  13 #define BLOCKSIZE       (RECORDSIZE * 20)
  14
  15 static char block[BLOCKSIZE];
  16 static unsigned long offset;
  17
  18 static time_t archive_time;
  19 static int tar_umask;
  20 static int verbose;
  21
  22 /* writes out the whole block, but only if it is full */
  23 static void write_if_needed(void)
  24 {
  25         if (offset == BLOCKSIZE) {
  26                 write_or_die(1, block, BLOCKSIZE);
  27                 offset = 0;
  28         }
  29 }
  30
  31 /*
  32  * queues up writes, so that all our write(2) calls write exactly one
  33  * full block; pads writes to RECORDSIZE
  34  */
  35 static void write_blocked(const void *data, unsigned long size)
  36 {
  37         const char *buf = data;
  38         unsigned long tail;
  39
  40         if (offset) {
  41                 unsigned long chunk = BLOCKSIZE - offset;
  42                 if (size < chunk)
  43                         chunk = size;
  44                 memcpy(block + offset, buf, chunk);
  45                 size -= chunk;
  46                 offset += chunk;
  47                 buf += chunk;
  48                 write_if_needed();
  49         }
  50         while (size >= BLOCKSIZE) {
  51                 write_or_die(1, buf, BLOCKSIZE);
  52                 size -= BLOCKSIZE;
  53                 buf += BLOCKSIZE;
  54         }
  55         if (size) {
  56                 memcpy(block + offset, buf, size);
  57                 offset += size;
  58         }
  59         tail = offset % RECORDSIZE;
  60         if (tail)  {
  61                 memset(block + offset, 0, RECORDSIZE - tail);
  62                 offset += RECORDSIZE - tail;
  63         }
  64         write_if_needed();
  65 }
  66
  67 /*
  68  * The end of tar archives is marked by 2*512 nul bytes and after that
  69  * follows the rest of the block (if any).
  70  */
  71 static void write_trailer(void)
  72 {
  73         int tail = BLOCKSIZE - offset;
  74         memset(block + offset, 0, tail);
  75         write_or_die(1, block, BLOCKSIZE);
  76         if (tail < 2 * RECORDSIZE) {
  77                 memset(block, 0, offset);
  78                 write_or_die(1, block, BLOCKSIZE);
  79         }
  80 }
  81
  82 static void strbuf_append_string(struct strbuf *sb, const char *s)
  83 {
  84         int slen = strlen(s);
  85         int total = sb->len + slen;
  86         if (total > sb->alloc) {
  87                 sb->buf = xrealloc(sb->buf, total);
  88                 sb->alloc = total;
  89         }
  90         memcpy(sb->buf + sb->len, s, slen);
  91         sb->len = total;
  92 }
  93
  94 /*
  95  * pax extended header records have the format "%u %s=%s\n".  %u contains
  96  * the size of the whole string (including the %u), the first %s is the
  97  * keyword, the second one is the value.  This function constructs such a
  98  * string and appends it to a struct strbuf.
  99  */
 100 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 101                                      const char *value, unsigned int valuelen)
 102 {
 103         char *p;
 104         int len, total, tmp;
 105
 106         /* "%u %s=%s\n" */
 107         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 108         for (tmp = len; tmp > 9; tmp /= 10)
 109                 len++;
 110
 111         total = sb->len + len;
 112         if (total > sb->alloc) {
 113                 sb->buf = xrealloc(sb->buf, total);
 114                 sb->alloc = total;
 115         }
 116
 117         p = sb->buf;
 118         p += sprintf(p, "%u %s=", len, keyword);
 119         memcpy(p, value, valuelen);
 120         p += valuelen;
 121         *p = '\n';
 122         sb->len = total;
 123 }
 124
 125 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 126 {
 127         char *p = (char *)header;
 128         unsigned int chksum = 0;
 129         while (p < header->chksum)
 130                 chksum += *p++;
 131         chksum += sizeof(header->chksum) * ' ';
 132         p += sizeof(header->chksum);
 133         while (p < (char *)header + sizeof(struct ustar_header))
 134                 chksum += *p++;
 135         return chksum;
 136 }
 137
 138 static int get_path_prefix(const struct strbuf *path, int maxlen)
 139 {
 140         int i = path->len;
 141         if (i > maxlen)
 142                 i = maxlen;
 143         do {
 144                 i--;
 145         } while (i > 0 && path->buf[i] != '/');
 146         return i;
 147 }
 148
 149 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 150                         unsigned int mode, void *buffer, unsigned long size)
 151 {
 152         struct ustar_header header;
 153         struct strbuf ext_header;
 154
 155         memset(&header, 0, sizeof(header));
 156         ext_header.buf = NULL;
 157         ext_header.len = ext_header.alloc = 0;
 158
 159         if (!sha1) {
 160                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 161                 mode = 0100666;
 162                 strcpy(header.name, "pax_global_header");
 163         } else if (!path) {
 164                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 165                 mode = 0100666;
 166                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 167         } else {
 168                 if (verbose)
 169                         fprintf(stderr, "%.*s\n", path->len, path->buf);
 170                 if (S_ISDIR(mode)) {
 171                         *header.typeflag = TYPEFLAG_DIR;
 172                         mode = (mode | 0777) & ~tar_umask;
 173                 } else if (S_ISLNK(mode)) {
 174                         *header.typeflag = TYPEFLAG_LNK;
 175                         mode |= 0777;
 176                 } else if (S_ISREG(mode)) {
 177                         *header.typeflag = TYPEFLAG_REG;
 178                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 179                 } else {
 180                         error("unsupported file mode: 0%o (SHA1: %s)",
 181                               mode, sha1_to_hex(sha1));
 182                         return;
 183                 }
 184                 if (path->len > sizeof(header.name)) {
 185                         int plen = get_path_prefix(path, sizeof(header.prefix));
 186                         int rest = path->len - plen - 1;
 187                         if (plen > 0 && rest <= sizeof(header.name)) {
 188                                 memcpy(header.prefix, path->buf, plen);
 189                                 memcpy(header.name, path->buf + plen + 1, rest);
 190                         } else {
 191                                 sprintf(header.name, "%s.data",
 192                                         sha1_to_hex(sha1));
 193                                 strbuf_append_ext_header(&ext_header, "path",
 194                                                          path->buf, path->len);
 195                         }
 196                 } else
 197                         memcpy(header.name, path->buf, path->len);
 198         }
 199
 200         if (S_ISLNK(mode) && buffer) {
 201                 if (size > sizeof(header.linkname)) {
 202                         sprintf(header.linkname, "see %s.paxheader",
 203                                 sha1_to_hex(sha1));
 204                         strbuf_append_ext_header(&ext_header, "linkpath",
 205                                                  buffer, size);
 206                 } else
 207                         memcpy(header.linkname, buffer, size);
 208         }
 209
 210         sprintf(header.mode, "%07o", mode & 07777);
 211         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 212         sprintf(header.mtime, "%011lo", archive_time);
 213
 214         /* XXX: should we provide more meaningful info here? */
 215         sprintf(header.uid, "%07o", 0);
 216         sprintf(header.gid, "%07o", 0);
 217         strlcpy(header.uname, "git", sizeof(header.uname));
 218         strlcpy(header.gname, "git", sizeof(header.gname));
 219         sprintf(header.devmajor, "%07o", 0);
 220         sprintf(header.devminor, "%07o", 0);
 221
 222         memcpy(header.magic, "ustar", 6);
 223         memcpy(header.version, "00", 2);
 224
 225         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 226
 227         if (ext_header.len > 0) {
 228                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 229                 free(ext_header.buf);
 230         }
 231         write_blocked(&header, sizeof(header));
 232         if (S_ISREG(mode) && buffer && size > 0)
 233                 write_blocked(buffer, size);
 234 }
 235
 236 static void write_global_extended_header(const unsigned char *sha1)
 237 {
 238         struct strbuf ext_header;
 239         ext_header.buf = NULL;
 240         ext_header.len = ext_header.alloc = 0;
 241         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 242         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 243         free(ext_header.buf);
 244 }
 245
 246 static int git_tar_config(const char *var, const char *value)
 247 {
 248         if (!strcmp(var, "tar.umask")) {
 249                 if (!strcmp(value, "user")) {
 250                         tar_umask = umask(0);
 251                         umask(tar_umask);
 252                 } else {
 253                         tar_umask = git_config_int(var, value);
 254                 }
 255                 return 0;
 256         }
 257         return git_default_config(var, value);
 258 }
 259
 260 static int write_tar_entry(const unsigned char *sha1,
 261                            const char *base, int baselen,
 262                            const char *filename, unsigned mode, int stage)
 263 {
 264         static struct strbuf path;
 265         int filenamelen = strlen(filename);
 266         void *buffer;
 267         char type[20];
 268         unsigned long size;
 269
 270         if (!path.alloc) {
 271                 path.buf = xmalloc(PATH_MAX);
 272                 path.alloc = PATH_MAX;
 273                 path.len = path.eof = 0;
 274         }
 275         if (path.alloc < baselen + filenamelen) {
 276                 free(path.buf);
 277                 path.buf = xmalloc(baselen + filenamelen);
 278                 path.alloc = baselen + filenamelen;
 279         }
 280         memcpy(path.buf, base, baselen);
 281         memcpy(path.buf + baselen, filename, filenamelen);
 282         path.len = baselen + filenamelen;
 283         if (S_ISDIR(mode)) {
 284                 strbuf_append_string(&path, "/");
 285                 buffer = NULL;
 286                 size = 0;
 287         } else {
 288                 buffer = read_sha1_file(sha1, type, &size);
 289                 if (!buffer)
 290                         die("cannot read %s", sha1_to_hex(sha1));
 291         }
 292
 293         write_entry(sha1, &path, mode, buffer, size);
 294         free(buffer);
 295
 296         return READ_TREE_RECURSIVE;
 297 }
 298
 299 int write_tar_archive(struct archiver_args *args)
 300 {
 301         int plen = args->base ? strlen(args->base) : 0;
 302
 303         git_config(git_tar_config);
 304
 305         archive_time = args->time;
 306         verbose = args->verbose;
 307
 308         if (args->commit_sha1)
 309                 write_global_extended_header(args->commit_sha1);
 310
 311         if (args->base && plen > 0 && args->base[plen - 1] == '/') {
 312                 char *base = xstrdup(args->base);
 313                 int baselen = strlen(base);
 314
 315                 while (baselen > 0 && base[baselen - 1] == '/')
 316                         base[--baselen] = '\0';
 317                 write_tar_entry(args->tree->object.sha1, "", 0, base, 040777, 0);
 318                 free(base);
 319         }
 320         read_tree_recursive(args->tree, args->base, plen, 0,
 321                             args->pathspec, write_tar_entry);
 322         write_trailer();
 323
 324         return 0;
 325 }